Thanks to everyone's contribution on this thread. It really helped, definitely as I confused on some parts in Danny's videos during the crossover assembly.
I just did the upgrade a week ago and your comments, Danny and New Record Day videos definitely helped in the decision to get it.
Here's my experience of it, the upgrade was not hard but definitely tedious+ required a little bit of thinking as it's my first time doing this(learned the basics of speaker crossover network and signal path along the way). You do feel satisfied after completing the full upgrade and hearing both speakers play perfectly. Now in terms of sound, I have the Klipsch RP-160M (yes I did check the crossover network and checked with Danny if it could be done to the RP-160M and he replied yes, as many others have done so). Had the RP-160M for nearly 3 years now and enjoyed it until I got the Magnepan LRS , Atohm GT1 and other speakers to play with. Then the V-curve of the Klipsch became extremely apparent in the original design, the highs/lows were too extended but not controlled enough with a lacking midbass. It does however play very loud for a bookshelf, filling up a large room easily without a sub and party level SPLs subs are added. But, since I stopped enjoying the Klipsch for Music in favour of the LRS kept it for movies only. I thought the $210 upgrade should be worth it if tames the highs, provides a better midbass punch and tighter bass. I didn't need an extended low end as I always planned of using subs for the sub 50hz notes. This is exactly what the modifications did for me and would be happy to recommend it if the above is what you are looking for. The frequency response curve showed by Danny fully explains what to expect with the stock vs GR research upgrade kit. So, don't think just because Speaker B appears brighter/louder/more detailed in New record Days comparison video, that Speaker A will sound muffled in real life. It is the complete opposite, the brighter sound of Stock Speaker B can be fatiguing if you have other more neutral speakers to compare it with, then you will enjoy the more balanced sound from the upgraded one. Also putting your ears next to the bass port when playing bass heavy songs, the No Rez effect on cabinet resonance can definitely be heard(from boxy sound to a much tighter bass, you may lose some low-end kick, in favour of more controlled/tighter mid-bass and bass). I would not recommend buying a new Klipsch + the upgrade, get another speaker that is already more balanced from GR Research or other brands. Do it if like me, you have enjoyed the Klipsch speakers for years, like the looks and overall power of the klipsch but keeps on wanting more, instead of selling it for cheap to buy a $1000+ speaker, just get the upgrade, it's well worth it.